The 1.1 version of CubeMapGen is available as a free download on our website. The program lies within Photo & Graphics Tools, more precisely Viewers & Editors. The actual developer of the free program is ATI Research Inc.
From the developer:
CubeMapGen is a tool for importing, filtering, visualizing, and exporting cubemaps.
Cubemaps can be assembled from separate face images that can be loaded into each cubemap face and interactively flipped vertically,
horizontally, and diagonally in order to align the faces.
Angular extent filtering and edge seam fixup provides new high quality filtering results for prefiltered environment mapping, and cubemap mipchain generation.
You may want to check out more software, such as Your Birthday News, SPX Editor or EDraw Soft Diagrammer, which might be related to CubeMapGen.